We don't always have to build up to fit more people into a city. Vancouver and Seattle offer alternative solutions.

Kitsilano, a lovely old neighborhood in Vancouver, British Columbia, looks much the same as it did a century ago when it was designed around a streetcar line. It still has enormous homes perched on lawns with alleys in the back, all within sight of downtown’s shimmering skyscrapers.

But unlike in 1930, when the neighborhood was home to a population of about 28,000, a lot more people live in Kitsilano now. By 2011, about 41,000 were living there. With family sizes smaller, the number of residences has increased by an even larger percentage. But just where are these new people and their homes if Kitsilano looks largely unchanged?

They are tucked away, here and there. The big old houses have been split up

at first illegally and then in recent years with the city’s encouragement. Developers and architects have gotten good at swelling these homes with additional rooms and floors without much altering their curb appearance. Along back alleys, new freestanding homes, locally called “laneway houses,” have been added.

The result is a lot more dwellings, and that density has several advantages. It keeps housing prices lower and gives more people a chance to live in a popular neighborhood. The large number of people make it more likely that a nice shop or café will open up. And it gives the area the population it needs to make transit work, be it bus, streetcar or a public bike program.

The one thing that hasn’t come to Kitsilano, however, is new tall buildings. The scale and character of the neighborhood has stayed much the same as it was when artists and hippies rediscovered the rundown area in the 1960s.

In debates over housing, there is often a false linkage between housing and height. If you want to substantially add housing, or what planning geeks call density, people sometimes talk as if you have no choice but to go up -- often by a lot. Sometimes developers and their advocates promote this dubious assertion.

It is an important issue, because as Americans and cities fall in love again with walkable neighborhoods, and with related amenities such as convenient transit and vibrant streetfront shopping, there also is a growing recognition that having more people per square foot makes these things possible. The Kitsilano method, which a planner friend of mine called “invisible density,” is one way to do it.

That’s not to suggest that nobody is putting up tall buildings in Vancouver. In the heart of downtown, for example, the city has its well known “point towers,” skyscraper-high apartment buildings atop street-level stores and businesses. They have given the city an identity and distinct skyline, as well as a lot of new homes.

In the nearby West End, though, the city is going for a mix of these two approaches. This district has both single-family homes and mid-rise apartment buildings. It would be nice to have more of the latter, say city planners. To allow this to happen, the city is beginning to tackle one of the most productive avenues for adding more housing: parking policies.

Michael Gordon, a senior downtown Vancouver planner, says the city is now researching parking in the West End with the idea of encouraging what is called “shared parking.” Under such a plan, a parking space in a private garage could serve more than one driver. Apartment buildings whose spaces are largely empty during the day could serve business traffic, and spaces in commercial buildings could serve residential parkers at night. If shared parking were possible, more buildings could be constructed without having to add parking spaces proportionally.

Reducing or even changing the supply of parking has long been an acutely sensitive subject, but Gordon believes this is changing because young people care less about parking. “We see a real generational divide,” Gordon says. “There are those who are all wound up about parking, and there are those who are really looking for a larger apartment so they can have a child or two.”

Other cities are exploring this as well. The popular Capitol Hill District in Seattle has produced a report called District Shared Parking that examines specific technologies that can be used to make the idea work. “A range of studies show that the more parking is decoupled from residential rent, the lower the cost of housing,” the report says. “Additionally, by only allowing one user for a given parking space, individual users are denied the opportunity to lower their costs through sharing. A well-designed shared parking system should reduce the amount of parking spaces built in new construction and further separate parking payments from residential and commercial rents.”

What is exciting is that technology, similar to that which is making Zipcars and Uber-style services possible, will probably make sharing a parking space easier. Apps and real-time feeds can tell us where parking spaces are available. When put in place with other policies, such as getting rid of minimum parking space requirements for new buildings, the result can be more housing at lower costs.

As many Americans and others embrace what some call urban lifestyles, and as the dream of the home in the suburbs with the three-car garage becomes less universal, just how to get to the kind of residential density that works becomes a more important issue. Understanding that adding homes doesn’t have to equal adding height is one step.